Which of the Following Uses the Doubling Method of Informal

Multiple Choice

Which of the following uses the doubling method of informal counting to solve the following:
3 + 4 =

A) (1 + 1 + 1) + (1 + 1 + 1 + 1) = 7
B) (3 + 4) + (3 + 4) - (3 + 4) = 7
C) 3 + 4 = (3 + 3) +1 = 6 + 1 = 7
D) 2 + 2 + 2 + 1 = 7